Medical inhalation device for the treatment of diseases of the respiratory tract

ABSTRACT

An inhalator is constructed with an outer housing and an inner protective housing. The outer housing includes an opening adapted to receive the anatomy of the nasal region. The outer housing also contains a reservoir for holding a supply of medicinal liquid. The inner housing contains and protects an oscillator which energizes an electromechanical transducer, the transducer extending through a wall of the protective housing in sealed relation thereto and carrying a vibratory atomizing member which is positioned to receive liquid from the reservoir. The oscillator includes a position sensitive on-off switch which permits operation only when the inhalator is in a predetermined orientation. A droplet shield is positioned forward of the atomizing member, between the atomizing member and the opening in the outer housing so that liquid droplets of the aerosol and respiration moisture precipitate thereon and run off along a path over which the droplets will not strike the atomizing member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ultrasonic liquid atomizer, and moreparticularly to an ultrasonic liquid atomizer for inhalation therapy.

2. Description of the Prior Art

Medicinal aerosols have heretofore been produced with devices which havea very expensive construction. Because of their weight and because theymust be connected to an electrical outlet, these commercially commonatomizing devices are very bulky and unwieldly for patient use.

SUMMARY OF THE INVENTION

It is therefore the primary object of the invention to provide a handdevice which is extraordinarily strong, light-weight and handy, andwhich permits operation independently of an electrical outlet.

This object is achieved in an ultrasonic liquid atomizer which includesan outer housing having an opening adapted to receive the anatomy of thenasal region and including therein a liquid reservoir for holding asupply of medicinal liquid, and an ultrasonic electromechanicaltransducer having an atomizer plate in fluid communication with thereservoir. Preferably, the oscillatory system includes an excitationcircuit which is connected to a piezoceramic layer carried on aconically-shaped sonic transducer which transmits ultrasonic flexuralwaves onto an atomizer plate carried by the transducer. Theconically-shaped sonic transducer is provided with a retaining ring at anode thereof and the retaining ring mounts the transducer in somewhat ofa cantilever fashion in a wall of a protective housing within the outerhousing, the protective housing containing the piezoceramic layer andthe excitation circuit. In one embodiment the reservoir is connected influid communication with the atomizing plate by way of a fluidpassageway which extends through the transducer in the plane of theretaining ring and then axially through the transducer and the atomizingplate. In another embodiment, the reservoir is provided with a fluidpassageway which extends toward the outer surface of the atomizingplate. In this embodiment, a mesh material functioning as a wick with acapillary-type action, may be provided to extend from the fluidpassageway over the outer face of the atomizing plate.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the invention, itsorganization, construction and operation will be best understood fromthe following detailed description, taken in conjunction with theaccompanying drawings, on which:

FIG. 1 is a schematic illustration of an embodiment of an inhalatorconstructed in accordance with the invention; and

FIG. 2 is a schematic illustration of another embodiment of an inhalatorconstructed in accordance with the invention and utilizing capillaryaction for feeding a medicinal liquid to an atomizing plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The atomizer of the present invention advantageously employs apiezoelectric oscillatory system, such as the system described in theGerman DOS No. 2,308,584 and in U.S. Pat. No. 3,904,896. Referring toFIG. 1, in the oscillatory system, flexural waves are generated by meansof a piezoceramic layer 1 and are transmitted by a conically-shapedtransducer 2 to an atomizer plate 3. In the region of an oscillationnode, the transducer is provided with a retaining ring 20 which mountsthe transducer in a freely-supported manner, in the wall of aliquid-proof protective housing 4 so that the piezoceramic layer isshielded from the liquid to be atomized. Additionally, an electronicexcitation circuit 10 is mounted in the protective housing 4. Theelectronic excitation circuit applies an alternating voltage to thepiezoceramic layer by way of an electrode 11 and an electrode 12. Theelectronic excitation circuit is supplied with a dc voltage, for examplebetween 6 and 12 volts by way of a feed line 101 which extends through awall of the outer housing 6 and a wall of the protective housing 4 in aliquid-type manner. The feed line 101 may be connected to a battery orto an outlet plug having a built-in rectifier. In case of operation froman electrical outlet, a higher dc voltage, for example 24 volts, ispreferred.

The atomizer plate 3 is supplied with liquid by way of a bore 30 whichextends along the longitudinal axis of the sonic transducer, and via afurther bore 21 which extends in the plane of the retaining ring 20. Theliquid is held in a container (reservoir) 5 which is preferably afunnel-shaped structure, the liquid being transported to the atomizerplate 3 by gravity. The liquid container 5 is, together with theoscillatory system, built into an atomizer housing 6. The housing 6 hasan opening in the vicinity of the atomizer plate 3, and an attachment 7can be emplaced, such as with a snap-on fit, which attachment is fittedto the anatomy of the nasal region. When the atomizer is operated, finemist droplets are produced by the atomizer plate and only the finestdroplets remain suspended and reach the attachment 7 for inhalation by apatient. The larger droplets fall down into the housing 6 and are caughtby the bottom wall of the housing. Advantageously, therefore, under theinfluence of gravity, the droplet size of the aerosol is homogenized.The liquid caught at the bottom of the housing can be transported, via areturn conduit 60, back into the liquid container 5 by simply tippingthe device.

When the device is not in use, the outlet opening can be closed with acover, which is emplaced instead of the attachment 7, againadvantageously by a snap-on engagement.

Preferably, a position dependent switch 13 is built into the protectivehousing, for example a mercury switch, so that the device automaticallyturns itself on when it is held in a working position, i.e., with theliquid container 5 located at the top, as illustrated on the drawings.In any other position, the electrical connection of the electronicexciter circuit to the current supply remains interrupted.

At a side of the housing, in the region of the liquid container 5, aviewing window 50 may be provided so that the liquid level can beascertained at any time.

In order to avoid having liquid drops blown against the transducer 2when the patient exhales, a drop shield 17 can be provided, which shieldis arranged above the transducer, or, respectively, the atomizer plate3, in the direction toward the housing opening, in such a way thatliquid drops of the aerosol and of the respiration moisture precipitateand run off on the front side 171 facing the housing opening. The frontside 171 extends in a vertical direction, looking toward the housingopening, above and forward of the position of the atomizer plate in sucha way that the drops running off no longer reach the oscillatory system,in particular onto the surface of the atomizer plate 3.

In order to refill the device, the medicinal liquid is simply pouredinto the housing 6, and the device is tipped so that the liquid flows tothe reservoir container 5 by way of the conduit 60.

It has been determined that particularly finely-particled aerosols canbe obtained with an inhalator constructed in accordance with theinvention if the excitation of the oscillatory system, i.e., theelectric power supplied to the oscillatory system, is dimensioned insuch a way that the operation of the oscillatory system or,respectively, the atomization, has a working point which is onlyslightly above the initiation threshold. The term "initiation threshold"is to be understood to mean the beginning of the oscillatory state ofthe oscillatory system or, respectively, of the atomizing plate. Withthe selection of this working point, it is advantageously achieved thatthe size distribution of the droplets is very homogeneous, even at lowoscillatory frequencies. With an inhalation device constructed inaccordance with the present invention, advantageous operation ispossible at oscillatory frequencies of 200 to 500 kHz. According toprevious findings, it was necessary to operate with frequencies in therange of MHz for relatively small droplets in the order of magnitude ofbetween 1 to 6 μm diameter, which requires considerable expense for theelectronics and also results in a lesser efficiency.

Referring to FIG. 2 now another embodiment of the invention isillustrated which is similar to that illustrated in FIG. 1 but whichdeviates therefrom in that the liquid supply onto the surface of theatomizer plate 3 takes place through a passageway 211 and via a networkstructure 317 which will be described in greater detail below, insteadof by way of the passageway 21, 30. The passageway 211 is located in apart 117 and extends, starting at the liquid container 5, in a downwarddirection to an outlet opening 217 which is situated above and spacedfrom the atomizer plate 3, the liquid from the container 5 reaching theopening 217 by means of gravity in all operating positions of theinhalation device.

Above and beyond the outlet opening 217 and the top of the atomizerplate 3, the above-mentioned network structure 317 is attached to thefront side 417 of the part 117, if necessary in an easily exchangeablefashion. Preferably, the front side 417 and the surface of the atomizerplate 3 lie in the same plane so that the network structure 317 restssmoothly, in suspension, on the surfaces.

The function of the network structure 317 is to transport the liquidfrom the outlet opening 217 to the surface of the atomizer plate 3 witha wick or capillary action. The dosage of the liquid supply occurs, onthe one hand, as a result of the selection of the cross section of thepassageway 211 and, on the other hand, by means of the wick or capillaryaction of the network structure 317.

Felted or matted cellulose fibers, such as for example a finely wovennetwork, as from Kleenex tissues, made of synthetic materials such asPerlon (a synthetic material similar to nylon) having mesh apertures of,for example, 100 μm and less, and the like are suitable as networkstructures for an inhalator constructed in accordance with theprinciples illustrated in FIG. 2. Advantageously, the network structure317 is not permitted to protrude substantially beyond the lower edge ofthe atomizer plate 3.

If necessary, a valve (not shown) is provided in all embodiments of theinvention, in the region of the passageway 21 or the passageway 211,with which the liquid flow out of the container 5 is blocked when thedevice is taken out of operation.

It can also be provided that the liquid container 5 be removable fromthe device or, respectively, interchangeable liquid containers may beprovided.

Although I have described my invention by reference to particularillustrative embodiments thereof, many changes and modifications of theinvention may become apparent to those skilled in the art withoutdeparting from the spirit and scope of the invention. I therefore intendto include within the patent warranted hereon all such changes andmodifications as may reasonably and properly be included within thescope of my contribution to the art.

I claim:
 1. A hand-held inhalator comprising:an outer housing includingmeans defining an opening shaped to receive the anatomy of the nasalregions; wall means defining an inner protective chamber within saidouter housing; an oscillator mounted within said inner chamber, saidoscillator including an electronic excitation and a piezoceramic memberelectrically connected to and excitable into vibration by saidelectronic excitation circuit, electrical supply leads connected to saidelectronic excitation circuit and extending in fluid-sealed relationthrough said chamber and outer housing for connection to an electricalsupply, and switch means electrically connected in said electricalsupply leads and operable to activate said electronic excitation circuitwhen said supply leads are connected to an electrical supply; aconically-shaped sonic transducer extending through said wall means andmounted thereto in a liquid-tight relation at an oscillation node, saidtransducer carrying said piezoceramic member on its larger end, andincluding an atomizing plate mounted on the smaller end of saidconically-shaped sonic transducer, said atomizing plate including asurface facing the opening in said outer housing, said transducertransmitting ultrasonic vibrations to said plate; and a liquid reservoirin said outer housing including an unobstructed outlet passageway meansand wick means providing sole fluid communication from said outletpassageway means to said surface of said atomizing plate.
 2. A hand-heldinhalator comprising:an outer housing including means defining anopening shaped to receive the anatomy of the nasal region; wall meansdefining an inner protective chamber within said outer housing; anoscillator mounted within said inner chamber, said oscillator includingan electronic excitation circuit and a piezoceramic member which isconnected to and excitable into vibration by said electronic excitationcircuit; a conically-shaped sonic transducer extending through said wallmeans and mounted thereto in a liquid-tight relation at an oscillationnode, said transducer carrying said piezoceramic member on its largerend, and including an atomizing plate mounted on the smaller end of saidconically shaped sonic transducer, said atomizing plate including asurface facing the opening in said outer housing, said transducertransmitting ultrasonic vibrations to said plate; and a liquid reservoirin said outer housing including an unobstructed outlet passageway meansextending from said reservoir to a point adjacent said atomizing plate,and a mesh network constituting a wick extending in fluid communicationbetween said outlet passageway means and said surface of said atomizingplate and providing sole fluid communication therebetween.